1. Field of the Invention
The present invention relates to stair chairs, and more particularly to a motorized sled for attachment to stair chairs to convert stair chairs into powered stair chairs for power-assisted stair ascents and descents.
2. Background and Related Art
Stair chairs are commonly used to maneuver patients in a variety of situations. Such situations include emergency response situations and evacuations of multi-level buildings. Stair chairs are typically designed to permit rolling movement of a patient or evacuee over flat surfaces and carrying of the stair chair up or down flights of stairs or over rough surfaces. Manufacturers of such chairs include Stryker Corporation of Kalamazoo, Mich. and Ferno-Washington, Inc. of Wilmington, Ohio. An illustrative stair chair 10 is shown in perspective view in FIG. 1.
The stair chair 10 includes rear bearings, typically wheels or casters 12, which permit the stair chair 10 to be rolled across a flat surface. In some stair chairs, no front wheels or casters are provided, and to roll the stair chair 10 across a surface, the user is expected to tip the stair chair 10 backward slightly until substantially all the weight of the stair chair 10 and a patient or evacuee thereon is over the rear wheels 12. In other instances, the stair chair 10 is provided with front casters 14, which permits rolling of the stair chair 10 without any tipping. The rear wheels 12 and the front casters 14 (if any) are typically attached to a chair frame 16. The chair frame 16 provides various support elements to support a patient or evacuee, such as a foot rest 18, a seat 20, and a back 22. For convenience in describing the stair chair 10, the chair frame 16 has been illustrated without any padding elements or other support surfaces for the seat 20 and the back 22.
The stair chair 10 may fold, such as at hinges 24, to make the stair chair 10 more compact for storage. The stair chair 10 may also be provided with handles 26 to assist responders in carrying the stair chair 10 up or down stairs or in otherwise moving the stair chair 10. The handles 26 nearest the foot rest 18 may be extendable so the responders or other users may more easily carry the stair chair 10 up or down stairs. When carried by the handles 26, the stair chair 10 is typically tipped back slightly so that the user at the foot of the stair chair 10 may stand upright while carrying the stair chair 10.
Stair chairs 10 are very useful in evacuating or otherwise moving patients or other people unable to move on their own. In a typical use situation, a patient is loaded onto the stair chair 10 (when the stair chair 10 is in its fully-unfolded state), the stair chair 10 is wheeled to the head or foot of a flight of stairs, and the stair chair 10 is then carried by two or more persons down or up the flight of stairs. Once any stairs have been navigated, the stair chair 10 is then wheeled further, either to additional stairs, to an ambulance, or to some other location where the patient is removed from the stair chair 10. Stair chairs 10 are often used in emergency situations where elevator service has been interrupted, is unavailable, or is inadvisable.